Cover with removable parts for electric furnaces



Dec. 7, 1965 A. RUMBERG ETAL 3,222,445

COVER WITH REMOVABLE PARTS FOR ELECTRIC FURNACES I5 Sheets-Sheet 1 Filed Feb. 10, 1964 [1V VEN TOR .5 H Urecl Bumbag Wrrwr Zinuws G iinZer li'ylfifemkazwen Wilhelm/Banyan R0 ATT 018% S Dec. 7, 1965 A. RUMBERG ETAL 3,222,445

COVER WITH REMOVABLE PARTS FOR ELECTRIC FURNACES 3 Sheets-Sheet 2 Filed Feb. 10, 1964 .mwmfwfi N E MWMUM N N mMmmMmu n U :A H O a V 0 HR M R N N fl F nKTH LE MM AW m Dec. 7, 1965 A. RUMBERG ETAL 3,222,445

COVER WITH REMOVABLE PARTS FOR ELECTRIC FURNACES Filed Feb. 10, 1964 3 Sheets-Sheet 5 5w lA/Vl-WTO s ALFRED RUM ERG, 7 I WgkNER KRAuss,

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W/LHE m DgMGEN 3 ROLF FRuHL/NG midi 6% ATTORNEVs United States Patent 5 Claims. for. 13 -9 This application is a continuation in part of application Serial No. 109,976, filed May 15, 1961, now abandoned.

Thepresent invention relates to a cover for electric arc furnaces, for example calcium carbide furnaces or metallurgic furnaces, which cover is provided with removable parts to facilitate the performance of work in the interior of the furnace.

Covers for relatively large electric arc furnaces generally consist of a cover plate having electrode-apertures or carrying the electrodes. The cover plate or middle part in these coversmay be suspended, supported on a .special framework or sit on a jacket which has the shape of a truncated cone or of a cylinder and rests on the upper rim of the tub of the furnace. The jacket, optionally provided with cleaning doors, may be designed removable as a whole or in part in all those cases in which the truncated cone or cylinder jacket doesnot receive the weight of the cover plate and of the electrodes.

The present inventionprovides a cover for electric arc furnaces the cover plate of which rests on a jacket having the shape of a truncated cone or of a cylinder, wherein individual cut-outs of the horizontal cover plate which has substantially a circular surface, and/ or parts of the jacket can be removed without impairing the stability of that portion of the cover plate which is left on the furnace and is not removed under normal service conditions.

The cover for electric arc furnaces according to the invention consists of a stable jacket which has the shape of a truncated cone or of a cylinder and may be provided with cleaning doors, and of a plate which is connected with the jacket in a gas-tight manner, receives the electrode-apertures, closes the top of the furnace and forms substantially a circular surface. In accordance with the invention, the jacket is provided with removable laterally bounded parts which are rigidly connected to laterally bounded cut-outs of the cover plate which reach from the outer edge of the cover plate to the allotted electrode. The lateral boundaries of the cut-outs of the plate are formed by tangents which converge in the direction of the electrode or are in parallel relationship with the connecting line between the axis of the furnace and the axis of the electrode and are tangent to the apertures receiving the electrodes or to a circle which is concentric with said electrode apertures, the diameter of this concentric circle being larger that that of the allotted electrode aperture.

According to a further embodiment of the present invention, the removable parts in the truncated cone or cylinder jacket are detachably connected with the removable bounded cut-outs of the cover plate, which advantageously rests on the jacket.

A cover with removable parts for electric furnaces constructed in accordance with the invention will now be described in greater detail by way of example with reference to FIGS. 1 to 7 of the accompanying drawings.

Referring to the drawings:

FIG. 1 is a longitudinal section taken along lines II of FIG. 2.

FIG. 2 is a top view of the same cover.

FIG. 3 is a top view of a modified form of construction of the cover of the invention.

FIG. 4 is a top view-of a removable cut-out.

FIG. 5 is a longitudinal section taken along lines V-V of FIG. 4.

FIG. 6 is a cross sectional view taken along lines VI-VI and VI'VI' of FIG. 4.

FIG. 7 is a cross sectional view taken along lines VII-VII and VII'VII of FIG. 4.

In the drawings, numeral 1 denotes the jacket which rests on .the brim of the furnace shell, numeral 2 denotes the cover plate remaining after the detachable cut-outs have been removed and which rests on the jacket or is suspended from a supporting frame. Numeral 3 denotes the electrode-receiving apertures in the cover plate 2 and numeral 4 denotes the removable cut-outs of cover plate 2. Numeral 5 denotes the removable parts of the jacket 1. The lining is not shown in the drawings.

The cover of the present invention comprises (a) the jacket 1 which has the shape of a truncated cone or of a cylinder the lower edge of which rests on the upper edge of the furnace shell, and (b) the cover plate 2 which is supported by jacket 1 and, in practice, substantially has the shape of a circular surface.

Cover plate .2 is provided with openings 3 through which the electrodes are led and with cut-outs 4 which reach from the allotted electrode to the outer edge of the cover plate and which, when the furnace is in operation, may be closed by parts of appropriate shape, advantageously ceramic parts.

Cut-outs 4 of the cover plate may be of various shape. In FIG. 2 they reach from the outer edge of cover plate 2 to the electrode-receiving aperture 3 and are bounded on the two other sides by straight lines which converge towards a point on the line connecting the axis of the electrode with the axis of the furnace.

In embodiment shown in FIG. 3, the straight lines bounding the cut-outs 4 are formed by tangents to the electrode-receiving aperture 3, which tangents are in parallel relationship with the line communicating between the axis of the electrode and the axis of the furnace.

In another embodiment, the parallels are designed tangent to a circle in concentrical relationship with the electrode-receiving apertures and having a diameter larger than the electrode apertures. In this manner, a more advantageous designing of stone sections is obtained since the pointed corners of cut-out 4 which are adjacent to the electrode are suppressed.

In the embodiments shown in FIGS. 2 and 3, parts 5 of jacket 1 may be rigidly connected to parts 4 closing the cut-outs of the cover plate 2. In this case, part 5 rigidly connected with part 4 is also removed when the latter is withdrawn.

Parts 4 and 5 may also be detachably connected with one another. In this case, part 4 may be removed, for example, while part 5 may remain in position or vice versa. Finally, parts 4 and 5 may be removed together when the connection detachable as such is left in position.

FIGS. 4 and 5 illustrate on an enlarged scale a mode of executing the detachable connections of the removable cut-outs 4 and 5 in the cover plate 2 and in the jacket 1, respectively. There are provided links 12 bridging the parting lines between cover plate 2 and removable cutout 4 and between jacket 1 and removable cut-out 5 thereof respectively, which links 12 are detachably fastened, on the one hand, to the stationary parts 1 and 2 and, on the other hand, to the removable parts 4 and 5. The

connection between parts 4 and 5 can be fixed, e.g., by Welding. In a modified structural form as shown in FIGS. 4 and 5, the parts 4 and 5 can be bolted together.

FIGS. 6 and 7 show these connections in greater detail. In FIG. 6, which corresponds to the cross-sectional views along lines VIVI and VI'-VI of FIG. 4, the rim portion of jacket 1 is bent in U-shaped manner with the formation of flanges 6 and 7. The rim portions of the removable jacket portion 5 are designed alike and result in the formation of flanges 8 and 9. The gap left between flanges 6 and 8 is filled with a packing 10 of heatresistant material, for example asbestos, to provide a gastight connection between parts 1 and 5. A link 12 resting for example on a layer of asbestos 11 and placed above the connecting point is secured by means of bolts or screws 13 and supporting disks 14 and 15. Ledge 16 serves to reinforce the junction point.

FIG. 7 corresponds to the cross sectional views taken along lines VIIVII and VIP-VII of FIG. 4. In this embodiment the upper rim of the removable part 5 of jacket 1 is provided with a rigidly connected, for example welded on flange 24, which together with a layer of packing material 22 disposed thereabove, for example asbestos, provides support for the rim 21 of part 4. Parts 21 and 24 are maintained in position relative to one another by means of screw bolt 17 provided with an electrically insulating sleeve 23 and electrically insulating supporting disks 19 and 25, the sleeve 23 and the supporting disks 19 and 25 consisting for example of micanite. The head of screw or bolt 17 and the nut thereof are seated on metal supporting disks 18 and 26 which provide mechanic protection for the insulating supporting disks 19 and 25. The flat iron collar 20 serves to reinforce the entire junction.

The cover of the present invention enables the watercooled protecting jackets of the so-called sockets to be replaced rapidly and in a simple manner. Parts of electrodes which may have been broken off can be easily removed from the furnace. The losses of heat of the charge are smaller since only at the position concerned in a given case parts of the cover need be removed.

We claim:

1. A cover for electric arc furnaces which comprises an annular jacket adapted to rest on the top annular edge of a furnace shell, a substantially circular cover plate supported by said jacket, apertures in said plate for accommodating electrodes, said apertures being disposed around the center of the cover plate, removable cut-outs in said cover plate extending from the outer edge of said plate to the allotted electrode apertures, and removable cut-outs in said jacket wall connected in depending relationship with said cutouts at the outer edges thereof, the edges of the cut-outs of said cover plates being straight lines converging in the direction of the electrodes when supported in the apertures and being tangent to the electrode apertures.

2. The cover of claim 1 wherein the connection between the removable cut-outs in the jacket, on the one hand, and the removable cut-outs in the cover plate, on the other hand, can be detached.

3. The cover of claim 1, wherein the cover plate rests on the jacket.

4. The cover of claim 1, wherein the jacket has the shape of a truncated cone.

5. The cover of claim 1, wherein the jacket has the shape of a cylinder.

References Cited by the Examiner UNITED STATES PATENTS 2,959,630 11/1960 Reschke 1 39 FOREIGN PATENTS 39,373 9/1915 Sweden.

RICHARD M. WOOD, Primary Examiner.

JOSEPH V. TRUHE, Examiner. 

1. A COVER FOR ELECTRIC ARC FURNACES WHICH COMPRISES AN ANNULAR JACKET ADAPTED TO REST ON THE TOP ANNULAR EDGE OF A FURNACE SHELL, A SUBSTANTIALLY CIRCULAR COVER PLATE SUPPORTED BY SAID JACKET, APERTURES IN SAID PLATE FOR ACCOMMODATING ELECTRODES, SAID APERTURES BEING DISPOSED AROUND THE CENTER OF THE COVER PLATE, REMOVABLE CUT-OUTS IN SAID COVER PLATE EXTENDING FROM THE OUTER EDGE OF SAID PLATE TO THE ALLOTTED ELECTRODE APERTURES, AND REMOVABLE CUT-OUTS IN SAID JACKET WALL CONNECTED IN DEPENDING RELATIONSHIP WITH SAID CUTOUTS OF THE OUTER EDGES THEREOF, THE EDGES OF THE CUT-OUTS OF SAID COVER PLATES BEING STRAIGHT LINE CONVERGING IN THE DIRECTION OF THE ELECTRODES WHEN SUPPORTED IN THE APERTURES AND BEING TANTENT TO THE ELECTRODE APERTURES. 